As celebrity wedding announcements go, North Korea's was terse. It was probably also three years out of date.

And it highlighted again how little is known about the impoverished nuclear-armed state and its ruling dynasty.

"Marshal Kim Jong-Un took part in the opening ceremony of Rungna People's Amusement Park with his wife, Comrade Ri Sol-Ju," state television reported late on Wednesday.

However brief and belated -- several reports said the marriage was in 2009 -- the announcement marked a new departure for an intensely secretive regime which previously kept the private lives of its rulers under wraps.

It ended weeks of speculation about the identity of a stylish young woman pictured accompanying the new young leader at official events this month.

Some South Korean media reports had suggested she was Jong-Un's younger sister Yo-Jong. One newspaper tentatively identified her as Hyon Song-Wol, a woman rumoured to be the leader's lover.

The North's state media has solved the mystery but given no details of Ri -- an omission which Seoul's media strove to remedy.

She is a former singer who caught Jong-Un's eye while giving a performance, some newspapers said.

One said Jong-Un's father Kim Jong-Il, who died last December after bequeathing power to his son, had singled her out as a future first lady while working on his succession plan.

The wife stirred especial interest because so little is known about her husband.

He was kept out of the public eye until preparations began in earnest several years ago for him to succeed his father. It was only in September 2010 that state media first published his adult photograph.

Outside North Korea, even Jong-Un's exact age is unclear. South Korea's National Intelligence Service (NIS) says he was born in January 1984, according to lawmakers who attended a private briefing Thursday.

The NIS has also gleaned a few facts about Ri, said to have been born in 1989. The couple were probably married in 2009 and there is speculation they have a child, it reportedly told legislators.

Ri attended a performing arts school and sang with the Unhasu orchestra even after she married, the spy agency reportedly said.

She was described as coming from an ordinary family -- newspapers said her father is an academic and mother a doctor.

She visited South Korea in 2005 as a cheerleader for her country's squad in the Asian Athletics Championships.

Cheong Seong-Chang of South Korea's Sejong Institute think-tank cast doubt on reports that Ri caught Jong-Un's eye while she was singing on stage.

Cheong believes the marriage was in 2009, with the couple thought to have had a child the following year.

"I doubt Ri maintained her life as a singer after marrying Jong-Un," he told AFP. "Such a theory is almost implausible in North Korea."

The academic also believes she is older than 23.

Whatever the factual uncertainties, Jong-Un is definitely projecting a different image to his late father, who did not expose his wife to the public eye and shrouded his own private life in secrecy.

Ri was photographed arm-in-arm with her husband this week as he smiled broadly and waved a sunhat at amusement park bathers.

Kim Jong-Il spoke just once at a major public event during his 17 years in power. His son has cultivated an outgoing and informal style, hugging soldiers, posing for photos with troops and linking arms with women.

His strategy is "to distance himself from his father and show he is more open, transparent and friendly to the people," Cheong said.

Disclosure of his marriage is seen as part of the general image-building, after Jong-Un's youth and inexperience raised questions about the country's second dynastic succession.

Publicising the marriage is part of efforts to stress his maturity in a culture which puts high priority on family life, analysts say.

The new regime's policy direction is still unclear. Public events can sometimes provide clues about the powers behind the throne, but not always.

Armed forces chief Ri Yong-ho was one of a small group who walked with Jong-Un beside his father's hearse last December.

But this month he was sacked in an apparent sign the leader was tightening his grip on the military.

Cheong said Jong-Un's appearances with his wife had 'raised expectations that he may take a path towards reform and openness'.

Other analysts are unsure whether there is substance behind the friendly style.

The International Crisis Group said in a report there was nothing to suggest Jong-Un would take measures to improve the lot of his people or reduce regional frictions over the North's nuclear and missile programmes.